A rocker arm controls opening and closing a valve in an internal combustion engine. A typical rocker arm includes a camming surface that engages a cam lobe of a cam shaft. Upon rotation of the cam shaft, the cam lobe urges one end of the rocker arm against a valve stem to open the valve. Upon further rotation of the cam shaft, a valve spring urges the valve closed.
The rocker arms are generally formed using methods known in the art, such as stamping, casting, and the like. The structure of the rocker arm must be sufficient to withstand the forces exerted by the cam lobe and valve stem and to withstand undesirable deformation during manufacture. Because the entire rocker arm reciprocates, however, the reciprocating mass of the rocker arm limits the engine's performance. Therefore, a need exists for a rocker arm having sufficient strength with a minimal mass.